**3. Pharmacological activities of banana**

Banana has various pharmacological effects. The prominent ones of more relevance to health care are discussed in this section.

## **3.1 Antioxidant activity**

Reactive oxygen species (ROS) are oxygen radicals with unpaired electron involved in both physiological and pathological conditions. Antioxidants, on the other hand, prevent free radical damage by scavenging the radicals. Banana contains various compounds that exert such antioxidant activity [21].

The antioxidant property of banana peel extracts *(Musa paradisiaca L.)* was explored using a group of rats exposed to a normal diet and compared to another group fed with fatty acid-rich diet. Oxidation markers like malondialdehyde (MDA) were measured. It was observed that subjects treated with banana peel extract displayed a significant decrease in concentrations of the peroxidation products (MDA), peroxides, as well as conjugated dienes. Meanwhile, antioxidant enzymes, catalase, and superoxide dismutase activities were raised significantly in the treated subjects. The level of an important antioxidant, reduced glutathione (GSH), also increased [22]. In another research conducted by [23], powdered candi banana (*Musa paradisiaca*) was extracted using ethanol and ethyl acetate in an ultrasonic bath. The results indicated that the antioxidant activity (IC50−50% inhibitory concentration) of ethanol extract and ethyl acetate was 3374.13 ± 123.46 and 40318.19 ± 1014.90 ppm, respectively, hence, leading to the conclusion that the antioxidant activity of ethanol extract is higher than that of ethyl acetate.

An *in vitro* antioxidant study of *Musa sapientum, Musa paradisiaca, Musa cavendish,* and *Musa acuminata* peels was conducted using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), hydrogen peroxide (H2O2) radical scavenging assay, and ferric reducing power assay. The results showed that *Musa acuminata* has the highest antioxidant activity followed by *Musa cavendish* against DPPH radical. In ferric reducing power and H2O2 scavenging assay, *Musa acuminata* also showed best antioxidant activity when compared with other extracts. The study revealed that the peels of *Musa* species possess significant *in vitro* antioxidant activity, hence, the conclusion that eating the peel of banana fruit would be beneficial considering its potential antioxidant property [24]. It was also reported that ethanol extracts of unripe Cavendish (*Musa acuminata L)* and Dream banana *(Musa acuminata colla. AAA cv* Berangan) peels have excellent radical scavenging activities with an IC50 of 90.28 μg/mL (for Cavendish) and 113.09 μg/mL (for Dream banana). The researchers ascribed this effect to the abundant phenols, flavonoids, and tannins detected in the peel extracts [25]. It can therefore be inferred that the antioxidant compounds like phenols and flavonoids present in the peel are involved in DPPH radical inhibition.

In another study that investigated the antioxidant activity of banana flowers of six distinct Malaysian cultivars, namely *Musa balbisiana* cultivars pisang Abu (P. Abu) and pisang Nipah (P. Nipah); *Musa acuminata* cultivars pisang Berangan (P. Berangan), pisang Susu (P. Susu), and pisang Mas (*P. Mas*); and *Musa paradisiaca* cultivar pisang Rastali (P. Rastali), it was found that, of all the six cultivars, P. Susu possess the highest phenolic content (80.13 ± 4.64 mg of GAE/g of extract) and the highest 2,2′-azido-bis (3-ethylbenzothiazoline-6-sulphonic acid) ABTS<sup>+</sup> and DPPH free radical scavenging activities. This is indicative of a strong relationship between the phenolic contents and radical scavenging power of the flowers [26]. The study of antioxidant activity of banana parts, namely tepal (methanol, ethanol, and aqueous extracts), peel, and pulp (methanol extracts) as well as pure syringin was carried out using DPPH radical scavenging assay and the result showed excellent antioxidant activity in tepal methanol extract, moderate activity in both tepal and peel ethanol and aqueous extracts. Meanwhile, mild activity was observed in pure syringin and pulp extracts. The DPPH radical scavenging activity of the different successive extracts of *Musa paradisiaca* showed direct proportion with sample concentration and the researchers attributed this role to the abundant phenols and flavonoids present in the extracts (**Figure 4**) [27]*.* DPPH and ferric ion reducing antioxidant power (FRAP) assay methods were employed to determine the radical scavenging ability of banana fruit extracts. The extract prepared from ethanol had higher antioxidant activity, while solvent hexane fraction showed moderate scavenging activity. Moreover, banana peels extracted with ethanol demonstrated potent antioxidant activity on DPPH, with an IC50 of 19.10 μg/mL. In the same vein, the ethanol extract of the peels exhibited significant antioxidant activity

**11**

*Pharmacological Activities of Banana*

**3.2 Anticancer effect**

**Figure 4.**

*3.2.1 Cytotoxic effects*

*DOI: http://dx.doi.org/10.5772/intechopen.83299*

on FRAP with IC50 values of 55.10 μg/mL. The pulp extracted with ethanol showed excellent FRAP radical scavenging activity with IC50 of 46.40 μM of Fe2+/mg [28]. A comparative study of antioxidant effects of banana and papaya peels was carried out using DPPD and ferric reducing activity methods. The outcome showed clearly that banana peel extract scavenges more free radicals than that of papaya [29].

*Antioxidant mechanism of flavonoids detected in banana. Enzymatic and/or chemical auto-oxidation of the flavonoids generates the flavonoid semiquinone radical, which may be scavenged by reduced glutathione (GSH), thereby generating the flavonoid and generating thiyl radical of glutathione. This thiyl radical may react with GSH to generate a disulfide radical anion which rapidly reduces molecular oxygen superoxide anion* 

*radical, which can be further detoxified by superoxide dismutase enzyme [71].*

Cancer is currently among the major world health concerns. It is characterized by abnormal cell growth. Natural products like banana are being utilized to combat the deadly disease. Banana is found to possess anticancer (colorectal) property by an *in vitro* assay of hill banana (Virupakshi). The fruit juice inhibits human colorectal adenocarcinoma cell line (HT-29) and causes mortality at a very low concentration [30]. It was hypothesized that CellQuest, a patented formula comprising high level of tannic acid (TA) extracted from *Musa paradisiaca* (plantain), suppressed the tumor cell proteasome activity. This study suggested that CellQuest aims at the proteasome selectively in tumor cells, which possibly contributes to the anticancer effect [31]. Anticarcinogenic substances present in banana peels like saponins can combat abnormal cells (**Figure 5**). The degree of anticancer effect corresponds to the degree of ripeness of the fruit. A research was conducted by a Tokyo university professor in which numerous health advantages of diverse fruits such as banana, grape, water melon, apple, pineapple, persimmon as well as pear were related. The result showed that banana displayed better augmentation of leucocytes, improve-

ment of body immunity, and production of anticancer substance [32].

Banana extracts were tested for their ability to suppress the growth of breast cancer cell line (MCF-7) and human colorectal carcinoma (HCT-116) tumor cell lines along with the human umbilical vein endothelial cells (HUVEC cell).

*Pharmacological Activities of Banana DOI: http://dx.doi.org/10.5772/intechopen.83299*

#### **Figure 4.**

*Banana Nutrition - Function and Processing Kinetics*

group fed with fatty acid-rich diet. Oxidation markers like malondialdehyde (MDA) were measured. It was observed that subjects treated with banana peel extract displayed a significant decrease in concentrations of the peroxidation products (MDA), peroxides, as well as conjugated dienes. Meanwhile, antioxidant enzymes, catalase, and superoxide dismutase activities were raised significantly in the treated subjects. The level of an important antioxidant, reduced glutathione (GSH), also increased [22]. In another research conducted by [23], powdered candi banana (*Musa paradisiaca*) was extracted using ethanol and ethyl acetate in an ultrasonic bath. The results indicated that the antioxidant activity (IC50−50% inhibitory concentration) of ethanol extract and ethyl acetate was 3374.13 ± 123.46 and 40318.19 ± 1014.90 ppm, respectively, hence, leading to the conclusion that the

antioxidant activity of ethanol extract is higher than that of ethyl acetate.

An *in vitro* antioxidant study of *Musa sapientum, Musa paradisiaca, Musa cavendish,* and *Musa acuminata* peels was conducted using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), hydrogen peroxide (H2O2) radical scavenging assay, and ferric reducing power assay. The results showed that *Musa acuminata* has the highest antioxidant activity followed by *Musa cavendish* against DPPH radical. In ferric reducing power and H2O2 scavenging assay, *Musa acuminata* also showed best antioxidant activity when compared with other extracts. The study revealed that the peels of *Musa* species possess significant *in vitro* antioxidant activity, hence, the conclusion that eating the peel of banana fruit would be beneficial considering its potential antioxidant property [24]. It was also reported that ethanol extracts of unripe Cavendish (*Musa acuminata L)* and Dream banana *(Musa acuminata colla. AAA cv* Berangan) peels have excellent radical scavenging activities with an IC50 of 90.28 μg/mL (for Cavendish) and 113.09 μg/mL (for Dream banana). The researchers ascribed this effect to the abundant phenols, flavonoids, and tannins detected in the peel extracts [25]. It can therefore be inferred that the antioxidant compounds like phenols and flavonoids present in the peel are involved in DPPH

In another study that investigated the antioxidant activity of banana flowers of six distinct Malaysian cultivars, namely *Musa balbisiana* cultivars pisang Abu (P. Abu) and pisang Nipah (P. Nipah); *Musa acuminata* cultivars pisang Berangan (P. Berangan), pisang Susu (P. Susu), and pisang Mas (*P. Mas*); and *Musa paradisiaca* cultivar pisang Rastali (P. Rastali), it was found that, of all the six cultivars, P. Susu possess the highest phenolic content (80.13 ± 4.64 mg of GAE/g of extract) and the highest 2,2′-azido-bis (3-ethylbenzothiazoline-6-sulphonic acid) ABTS<sup>+</sup> and DPPH free radical scavenging activities. This is indicative of a strong relationship between the phenolic contents and radical scavenging power of the flowers [26]. The study of antioxidant activity of banana parts, namely tepal (methanol, ethanol, and aqueous extracts), peel, and pulp (methanol extracts) as well as pure syringin was carried out using DPPH radical scavenging assay and the result showed excellent antioxidant activity in tepal methanol extract, moderate activity in both tepal and peel ethanol and aqueous extracts. Meanwhile, mild activity was observed in pure syringin and pulp extracts. The DPPH radical scavenging activity of the different successive extracts of *Musa paradisiaca* showed direct proportion with sample concentration and the researchers attributed this role to the abundant phenols and flavonoids present in the extracts (**Figure 4**) [27]*.* DPPH and ferric ion reducing antioxidant power (FRAP) assay methods were employed to determine the radical scavenging ability of banana fruit extracts. The extract prepared from ethanol had higher antioxidant activity, while solvent hexane fraction showed moderate scavenging activity. Moreover, banana peels extracted with ethanol demonstrated potent antioxidant activity on DPPH, with an IC50 of 19.10 μg/mL. In the same vein, the ethanol extract of the peels exhibited significant antioxidant activity

**10**

radical inhibition.

*Antioxidant mechanism of flavonoids detected in banana. Enzymatic and/or chemical auto-oxidation of the flavonoids generates the flavonoid semiquinone radical, which may be scavenged by reduced glutathione (GSH), thereby generating the flavonoid and generating thiyl radical of glutathione. This thiyl radical may react with GSH to generate a disulfide radical anion which rapidly reduces molecular oxygen superoxide anion radical, which can be further detoxified by superoxide dismutase enzyme [71].*

on FRAP with IC50 values of 55.10 μg/mL. The pulp extracted with ethanol showed excellent FRAP radical scavenging activity with IC50 of 46.40 μM of Fe2+/mg [28]. A comparative study of antioxidant effects of banana and papaya peels was carried out using DPPD and ferric reducing activity methods. The outcome showed clearly that banana peel extract scavenges more free radicals than that of papaya [29].

#### **3.2 Anticancer effect**

Cancer is currently among the major world health concerns. It is characterized by abnormal cell growth. Natural products like banana are being utilized to combat the deadly disease. Banana is found to possess anticancer (colorectal) property by an *in vitro* assay of hill banana (Virupakshi). The fruit juice inhibits human colorectal adenocarcinoma cell line (HT-29) and causes mortality at a very low concentration [30]. It was hypothesized that CellQuest, a patented formula comprising high level of tannic acid (TA) extracted from *Musa paradisiaca* (plantain), suppressed the tumor cell proteasome activity. This study suggested that CellQuest aims at the proteasome selectively in tumor cells, which possibly contributes to the anticancer effect [31]. Anticarcinogenic substances present in banana peels like saponins can combat abnormal cells (**Figure 5**). The degree of anticancer effect corresponds to the degree of ripeness of the fruit. A research was conducted by a Tokyo university professor in which numerous health advantages of diverse fruits such as banana, grape, water melon, apple, pineapple, persimmon as well as pear were related. The result showed that banana displayed better augmentation of leucocytes, improvement of body immunity, and production of anticancer substance [32].

#### *3.2.1 Cytotoxic effects*

Banana extracts were tested for their ability to suppress the growth of breast cancer cell line (MCF-7) and human colorectal carcinoma (HCT-116) tumor cell lines along with the human umbilical vein endothelial cells (HUVEC cell).

**Figure 5.** *Mechanism of pro-apoptotic effect of saponins, compounds present in banana [72].*

The extracts showing more than 60% inhibition of cell proliferation were the active extracts. Among these, hexane extract of banana peel and pulp showed maximum toxicity against HCT-116 and MCF-7 cell lines with percentages of 62.04 and 61.21%, respectively, while the aqueous and ethanol extracts indicated low anti-proliferative activity against HCT-116 and MCF-7. Interestingly, all the tested extracts showed virtually no cytotoxic effect against the normal cell lines [28].

#### *3.2.2 Anti-angiogenic activity*

In a research that assessed the anti-angiogenic potential of different banana extracts, rat aorta ring assay was employed using suramin as a reference drug. Banana extracts exhibiting over 60% inhibition of sprouting of blood vessels were considered active extracts. Two extracts exhibited potent inhibitory activity (>60%) with maximum inhibition of 85.32% produced by the hexane extract of banana peel. These significant inhibition values were very much similar with the standard drug (suramin), which showed potent inhibition of microvessel growth [28].

#### **3.3 Antiulcer activity**

Ulcer has been a major challenge of developing nations. It is a lesion caused by factors including the bacteria *Helicobacter pylori* and excess acidity. Researchers tested the potency of banana against this complication and it was shown to have significant antiulcer activity by [33] who evaluated the ulcer index, gastric wall mucus, gastric juice pH, and volume of ulcer-induced animals. The results showed the preventive effect of tepal and peel extracts against indomethacin plus pylorus ligation-induced ulcer by 68.80 ± 20.53 and 43.22 ± 14.82%, respectively. In addition, reduced gastric juice volume and increased gastric wall mucus were observed in both the tepal and peel extract-treated groups. Finally, the study revealed that banana tepal and peel extracts were able to prevent the induced ulcer by strengthening the gastric mucosa and decreasing the acidity of the gastric juice. In another study on the antiulcer effects of chloroform and ethanol extracts of banana, in ulcer-induced rats by ethanol, it was found that, both the chloroform (200 mg/kg) and ethanol extracts (400 mg/kg) were effective against the induced ulcer by significantly (p < 0.05) reducing the number of ulcer and ulcer index as compared to the standard ulcer drug, ranitidine [34].

**13**

*Pharmacological Activities of Banana*

unripe plantain were explored.

**3.4 Antidiabetic effect**

**3.5 Antimicrobial activity**

*DOI: http://dx.doi.org/10.5772/intechopen.83299*

Leucocyanidin showed protective effect against ulcer induced by aspirin. The compound was extracted from *Musa paradisiaca* (plantain) by solvent fractionation and was described as the active antiulcer compound [35]. Dried plantain pulp powder is a potent herbal drug for the treatment of peptic ulcer disease as suggested in a research conducted by [8], in which the ulcer protective and curing activities of

Diabetes, which can be insulin dependent or non-insulin dependent, poses a great threat to humanity. High level of glucose is prominent in diabetic patients and attempts have been made to counteract that using several plants including banana. Investigation into the anti-hyperglycemic effect of ethanol extract of *Musa sapientum* (*EMS*)*, M. paradisiaca (EMP), Musa cavendish (EMC),* and *M. acuminata (*EMA) peels by oral glucose tolerance test in glucose-loaded (2 g/kg p.o) normoglycemic (having normal concentration of glucose) rats was done by [24]. It was observed from this study that animals treated with EMC (500 and 1000 mg/ kg, p.o) and EMA (200 and 400 mg/kg p.o) showed marked anti-hyperglycemic effect (p < 0.01). Also, both EMS (200 mg/kg, p.o) and EMP (500 mg/kg, p.o) depicted significant (p < 0.01) decrease in blood glucose level. Another study aimed at evaluating the *in vitro* antidiabetic activity of methanol extracts of three kinds of fruit peels (lemon, pomegranate, and banana) showed that banana peel exhibited maximum alpha amylase inhibitory activity (80.87% at 1000 μg/mL). Hence, banana peel is more potent among the three, having the highest hypoglycemic effect. Thus, it can be utilized as antidiabetic supplement as compared to the others [36]. The hypoglycemic effect of methanolic extract of mature green fruits of *M. paradisiaca* in normal (normoglycemic) and streptozotocin-induced diabetic (hyperglycemic) mice was evaluated. The results of this experiment indicated that the extract possesses hypoglycemic activity, and hence corroborate folkloric use of the plant in the management of type-2 diabetes mellitus [37]. The effect of *M. sapientum* Linn. sucker administration on pancreas histology, fasting blood glucose as well as body weight in experimental animals made hyperglycemic by alloxan induction were reported by [38]. The sample was found to effectively reduce the glucose level, improve the animal's body weight, and regenerate the damaged pancreas in the induced rats. Hence, banana is perhaps the best candidate for diabetic control.

The antimicrobial properties of ethanol and acetone extracts of banana peels were evaluated by well diffusion assay against different microbial strains. An 80% acetone extract inhibited bacterial species at 600 ppm against Gram-positive bacteria including *Bacillus subtilis* (20.60%), *Staphylococcus aureus* (19.75 mm), *Escherichia coli* (18.15 mm), and *Pseudomonas aeruginosa* (19.57 mm). The presence of phytochemicals including phenolic compounds and tannins is believed to be associated with this antimicrobial property [39]. The Kirby-Bauer sensitivity method was employed to evaluate the antibacterial activity of silver (Ag) nanoparticles synthesized from the stem waste of banana plant. The Ag nanoparticles showed remarkable activity against *E. coli* and *Staphylococcus epidermidis*, with *E. coli* (Gram negative) being more susceptible with an inhibition zone of 12 mm. The research showed that banana stem waste can generate Ag nanoparticles with antibacterial activity against Gram-negative bacteria, *E. coli,* and *S. epidermidis* [40]. In a separate work, fresh green and yellow banana peel of (*Musa*, cv. *cavendish*) fruits treated with 70% acetone were sequentially partitioned with chloroform (CHCl3) and ethyl acetate

Leucocyanidin showed protective effect against ulcer induced by aspirin. The compound was extracted from *Musa paradisiaca* (plantain) by solvent fractionation and was described as the active antiulcer compound [35]. Dried plantain pulp powder is a potent herbal drug for the treatment of peptic ulcer disease as suggested in a research conducted by [8], in which the ulcer protective and curing activities of unripe plantain were explored.
